About "D class amp" idea from Variac; It's my dream project. But, it seems I have to wait untill this technolgy develops a bit more (became more available should I say?). I have to live with my existing bass amp head untill then

I don't think this is true. Instrument speakers, even those used in open backed cabinets (open baffle) don't tend to have much excursion.

What is true is this:

Quote:

most of these guitar amps/combos use the advantage of having limited frequency ranges that do not cause over excursion and cone displacement, as they don't reach very low frequencies.

I believe that your trumpet doesn't go as low as a guitar, so....you have even more advantage. Open baffle should work wonderfully for you. Probably even with the effects box.

You couldn't use the driver bare, without a baffle,- the low notes would be missing. BUT , if you are using just the natural range of the trumpet it could be pretty small. IT should probably be placed on the floor. The great advantage of this is that the part on the floor acts like an extremelty large baffle edge, because no sound can get around that part. So your stage fantasy setup could be a panel about 30" by 3' high maybe. I like the bigger, folding idea..

Here's a chance to do DIY EXPERIMENTATION.

Just go to your hardware store and buy a 4'x8' piece of MDF.
It looks like heavy particle board. In 3/4" it should be less than $25.

Cut a hole in it for your bass driver and bolt it in.

TRY IT OUT!!!!!!

Of course the highs will be missing, but see if the bass is enough..

Now try other sizes- cut it into a 4'x4' piece, a 3x4, 3x3 a 2x4 and try them out- sometimes with the long side on the floor , sometimes the short.

For once, physics is gonna help you here. To go one octave lower you need a baffle twice as big. So, for a bass , you would probably need a pretty big baffle- at least 4x4, probably 4x6. But since the trumpet doesn't go so low, your bafle might be reasonable. I've see openbacked bass cabs that are about 36" high by 30" wide, (with 6" sides though which counts as size) so geven for bass, I don't hink ift would HAVe to be too big. heck , try the different baffle sizes with your bass.

I have heard that most of the bass guitar energy is the first harmonic, and that's what you mostly hear. The first harmonic is actually a lot louder than the fundamental...

15" drivers can go a lot higher than people think, so your choice of bass and tweeter drivers might not be optimal, but just might work. The tweeter has similar issues to the bass driver- the lower you cross it , the less power it can take due to excessive excursion. IF you don't over power to the thing, it can go lower. Usually the documentation will tell you how much power it can handle and different crossover frequencies. If it can go down to 2000 that would be better than 3000 for the sound, but makes it more fragile

Please report back here with your results. I put some time into my answer here, so you owe me!!!

As a quick progress report, after two work days spended in carpenter's with trying some different woods and sizes for an open baffle (a piece of flat plywood actually) I ended up with something like this:

Why? Well, an open baffle could be the most suited configuration for trumpet soundwise. But physical aspects (durability, handling, positioning at different stages etc.) became an increasing concern in my mind while I was there (carpenter's).

At least I tried, didn't I

I attached the woofer and corner protectors temporarily for picturing, since the cabinet is not finished yet. There will be a tweeter there somewhere Sealing should be secured (I may ask about sealer later ). Internal padding and a grill for woofer are also in the list.